Picked up image recording system, signal recording device, and signal recording method

ABSTRACT

When a recording start executed in a variable-speed recording mode, at ST 44  a signal having a variable frame rate is selected on the basis of a validity signal from among image signals having a predetermined output frame rate in which the images having the variable frame rate are contained and stored in a memory. If it is decided at ST 46  that a phase difference between a write position and a read position in the memory has reached a recording start level, the stored signal is recorded in a recording medium at ST 47.  If it is decided at ST 48  that the phase difference has decreased to a recording stop level, recording to the recording medium is stopped at ST 49.  When an end operation is executed at ST 51,  the signal in the memory is recorded in the recording medium to then end actions. The signals are selected and recorded, thus resulting in a smaller signal quantity. Further, if the variable frame rate is varied, video effects can be confirmed only by reproducing the recorded signals.

TECHNICAL FIELD

The present invention relates to a shot-image-recording system andsignal-recording device and method

BACKGROUND ART

In conventional movie production etc., to obtain special video effects,a shooting speed of a film camera, that is, the number of frames persecond during the shooting varies. For example, if the shooting is madeat a speed higher than an ordinary one and played back at the ordinaryspeed, images are reproduced slowly. Therefore, it is possible toobserve easily and in detail a slow motion of, for example, a waterdroplet falling on a water surface. If the shooting is made at a speedlower than an ordinary one and played back at the ordinary speed, on theother hand, images are reproduced speedily. Therefore, it is possible topresent images having high realistic sensations in which a speedsensation is increased in a scene of a fight, car chase, etc.

Further, while in TV program production etc., the digitalization ofshooting, editing, broadcasting, etc. for a program has beenconventionally involved, film making, etc. is also intended to bedigitalized recently owing to improvements in picture quality anddecreases in equipment cost as digital technologies has progressed.

Note here that in a case where images are shot using a video cameraowing to digitalization of film making etc., to obtain theabove-mentioned special video effects, for example, not only imagesignals obtained by shooting at a predetermined speed but also imagesignals obtained by shooting at a high speed or a low speed are allrecorded in a recording device such as a server so that an image signalof frame images required to obtain the special video effects may be readfrom these recorded image signals to process the images, therebycreating the image signal that provides special video effects.

In such a manner, the image signals shot at several frame rates are allrecorded in the server, so that the server needs to have a large storagecapacity. Further, to confirm the special video effects, the imagesignals must be read from the server to perform image processing, sothat those effects cannot be confirmed readily at, for example, a siteof film making.

Further, to easily obtain the special video effects such as high speedplayback or slow playback, a shooting device that is possible to vary aframe rate during shooting (see, for example, Japanese PatentApplication. Laid-open Publication No. 2000-125210) is used to shoot ata frame rate lower than a predetermined one and then, the reproductionthereof is executed at the predetermined frame rate, thereby easilyobtaining high-peed playback images. Alternatively, by shooting at ahigher frame rate and then, the reproduction thereof is executed at thepredetermined frame rate, slow playback images can be obtained easily.However, in the case of recording an image signal output from thisshooting device, if a recording device has a constant recording framerate, an image signal having this recording frame rate is generated sothat the number of effective picture frames corresponding to the framerate at the time of shooting may be contained in this image signal.Therefore, if recording the image signal output from the shooting deviceat the recording frame rate, it is impossible to efficiently record onlya signal having a required effective picture frame rate.

DISCLOSURE OF THE INVENTION

The present invention provides a shot-image-recording system forrecording an image shot by a shooting device in a recording medium usinga signal-recording device, wherein the shooting device comprisesshooting means for generating image signal having a shooting frame ratefrom a shot image, frame-addition-processing means for adding a frame onthe basis of the image signal generated by the shooting means andoutputting an image signal having a predetermine output frame rate inwhich the shot image is contained at a variable frame rate together witha validity signal indicating frame of the image having the variableframe rate in the image signal having the output frame rate, andshooting control means for controlling operations of the shooting meansand the frame-addition-processing means on the basis of aframe-rate-setting signal, to vary the shooting frame rate and/or switchthe number of add frames in the frame addition so that the variableframe rate may be set to a frame rate based on the frame-rate-settingsignal, and wherein the signal-recording device comprises storage means,storage control means for selecting an image signal of the image havingthe variable frame rate from among the image signal having the outputframe rate on the basis of the validity signal and storing it in thestorage means, recording means for recording the signal in the recordingmedium, and recording control means for recording the signal stored inthe storage means in the recording medium intermittently at apredetermined recording frame rate in accordance with a signal quantityof the image signal stored in the storage means.

This recording control means uses a phase difference between a writeposition and a read position for the signal as the signal quantity ofthe image signal stored in the storage means. Furthermore, thesignal-recording device comprises image compression means, which imagecompression means compresses the image signal of the image having thevariable frame rate, while the storage control means stores thecompressed image signal in the storage means.

Further, this shooting control means generates additional informationrelevant to the image having the variable frame rate, while the storagecontrol means stores the additional information together with the imagesignal of the image having the variable frame rate in the storage means.Furthermore, the image signal having the output frame rate is a signalof a common data rate (CDR) system.

A signal-recording device relative to the present invention forrecording a signal using an image signal having a predetermined outputframe rate in which an image having a variable frame rate is containedand a validity signal indicating a frame of the image having thevariable frame rate with respect to the image signal comprises storagemeans, storage control means for selecting the image signal of the imagehaving the variable frame rate from among the image signal on the basisof the validity signal and storing it in the storage means, recordingmeans for recording the signal stored in the recording medium, andrecording control means for recording the signal stored in the storagemeans in the recording medium intermittently at a predeterminedrecording frame rate in accordance with a signal quantity of the imagesignal stored in the storage means.

This recording control means uses a phase difference between a writeposition and a read position for the signal as the signal quantity ofthe image signal recorded in the storage means. Furthermore, itcomprises image compression means, which image compression meanscompresses the image signal of the image having the variable frame rate,while the storage control means stores the compressed image signal inthe storage means.

A signal-recording method related to the present invention for recordinga signal using an image signal having a predetermined output frame ratein which an image having a variable frame rate is contained and avalidity signal indicating a frame of the image having the variableframe rate with respect to the image signal comprises the steps ofselecting an image signal of the image having the variable frame ratefrom among the image signal on the basis of the validity signal andstoring it in the storage means and recording the signal stored in thestorage means in the recording medium intermittently at a predeterminedrecording frame rate in accordance with a signal quantity of the imagesignal stored in the storage means.

This method further comprises a step of using a phase difference betweena write position and a read position for the signal as the signalquantity of the recorded image signals. Furthermore, the method furthercomprises steps of compressing the image signal of the image having thevariable frame rate and storing the compressed image signal in thestorage means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a configuration of a shot-image recording system;

FIG. 2 shows a configuration of a shooting device;

FIG. 3 shows a configuration of a frame-addition-processing unit;

FIG. 4 is a flowchart for showing operations to set the number of addframes in accordance with a variable frame rate and a shooting framerate;

FIG. 5 is a diagram for showing a relationship between additionswitchover information and a shooting frame rate;

FIG. 6 is a diagram for showing an outlined configuration of an FIT-typeCCD;

FIGS. 7A-7C are diagrams for explaining a blanking interval and a validscreen period in a case where a CDR system is used;

FIGS. 8A-8H and 8J-8N are diagrams for explaining operations in the caseof adjusting duration of a horizontal-blanking interval;

FIGS. 9A-9G are diagrams for explaining operations in the case ofadjusting duration of a vertical blanking interval;

FIG. 10 is a flowchart for showing a frame addition operation;

FIG. 11 is a flowchart for showing read accommodation processing;

FIGS. 12A-12G are diagrams for showing operations in a case where thenumber of add frames is “3”;

FIGS. 13A-13E are diagrams for showing a signal selector set position ina case where the number of add frames is “3”;

FIGS. 14A-14G are diagrams for explaining operations to vary an outputframe rate (in a case where the number of frames is not varied);

FIGS. 15A-15G are diagrams for explaining operations to vary the outputframe rate (in a case where the number of frames is varied);

FIG. 16 is a diagram for showing a configuration of a signal-recordingdevice;

FIG. 17 is a diagram for showing a configuration of a storage-processingunit;

FIG. 18 is a flowchart for showing a signal-recording operation;

FIGS. 19A-19B are diagrams for explaining write/read operationsperformed to an image memory; and

FIG. 20 is a flowchart for explaining a playback operation.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will describe a best embodiment with reference todrawings. FIG. 1 shows a configuration of a shot-image-recording system.

A shooting device 10 is constituted using a solid image pickup devicesuch as a charge coupled device (CCD) and so varies a frame rate(hereinafter referred to as “shooting frame rate”) FRp of this imagepickup device or adding up image signals having a shooting frame rateFRp which is based on a signal output from the image pickup device andcontrolling the number of additions, thereby generating an image signalof images having a variable frame rate FRc corresponding to a shot imagein which the number of frames per second varies. Furthermore, itgenerates an image signal having a predetermined output frame rate Fcfrom among the image signals having the variable frame rate FRc and avalidity signal indicating a frame of an image having the variable framerate FRc in this image signal having the output frame rate Fc andsupplies them to a signal-recording device 70. Further, an electronicviewfinder (EVF) 100 is connected to the shooting device 10, so that byusing this electronic viewfinder 100 to display shot images etc.,shooting conditions, for example, an angle of view and brightness, areconfirmed.

The signal-recording device 70 selects a signal of an image having thevariable frame rate FRc indicated by the validity signal from among theimage signals having the output frame rate Fc and records this selectedsignal in a recording medium at a recording frame rate Fe which is equalto, for example, the output frame rate Fc. Further, when reproducing therecording medium, it generates an image signal having a desired displayframe rate Ff and supplies it to an image display device 110, so thatthe image display device 110 displays reproduced image.

FIG. 2 shows a configuration of the shooting device 10. Light comingthrough an imaging lens system 11 enters a shooting unit 21, so that animage of an object is formed on an imaging surface of the image pickupdevice. The image pickup device generates a shot charge of the objectimage by photoelectric transfer and reads the shot charge on the basisof a drive control signal RD from a later-described drive unit 62 toconvert it into a voltage signal. Further, it supplies this voltagesignal as a three-primary-color image signal Spa to a pre-processingunit 22.

The pre-processing unit 22 performs processing to remove a noisecomponent from the image signal Spa, for example, correlation doublesampling and supplies the noise-free image signal Spa as an image signalSpb to an A/D conversion unit 23. The A/D conversion unit 23 convertsthe image signal Spb into a digital image signal DVa and supplies it toa feedback clamp unit 24. Further, based on an error signal suppliedfrom the feedback clamp unit 24, it corrects the operation of convertingthe image signal Spb into the image signal DVa. The feedback clamp unit24 detects an error between a black-level signal and a reference signalduring a blanking interval and supplies it to the A/D conversion unit23. It is thus possible to obtain an image signal DVa having a stableblack level and a desired magnitude by using the A/D conversion unit 23and the feedback clamp unit 24.

A correction-processing unit 25 performs shading correction on the imagesignal DVa, correction processing on defectiveness in the image pickupdevice, correction of a lens aberration of the imaging lens system 11,etc. The image signal DVa that has undergone the correction processingby this correction-processing unit 25 is supplied as an image signal DVbto a frame-addition-processing unit 30 and a frame rate conversion unit35.

Although in this embodiment, the three-primary-color image signal Spa isoutput from the shooting unit 21, a luminance signal and acolor-difference signal may be output. Further, the signals are notlimited to color image signals; for example, an image signal ofblack-and-white images etc. may be output. Further, the pre-processingunit 22, the feedback clamp unit 24, the correction-processing unit 25and an output-signal-processing unit 41 and a monitor-signal-processingunit 51, both of which are described later, are provided to obtain agood quality shot image and not in all cases necessary to constitute theshooting device. For example, the image signal Spa may be converted intoa digital signal by the shooting unit 21 to be then supplied as theimage signal DVb to the frame-addition-processing unit 30 and the framerate conversion unit 35. Further, the signal may be output not via theoutput-signal-processing unit 41 or the motion-signal-processing unit51.

The frame-addition-processing unit 30 performs frame addition processingby use of the image signal DVb on the basis of a control signal CT froma later-described shooting control unit 60. FIG. 3 shows a configurationof the frame-addition-processing unit 30. The image signal DVb suppliedfrom the correction-processing unit 25 is fed to an adder 301 and asignal selector 302 at its terminal Pa. Further, the adder 301 issupplied with an image signal DVf from a later-described signal selector305. The adder 301 supplies the signal selector 302 at its terminal Pbwith an added-up signal DVg obtained by adding up the supplied imagesignals DVb and DVf.

A movable terminal Pm of the signal selector 302 is connected to amovable terminal Pm of the signal selector 303. This signal selector302, based on a control signal CTa from the shooting control unit 60,selects either the image signal DVb supplied to the terminal Pa or theadded-up signal DVg supplied at the terminal Pb and supplies it as animage signal DVc to the signal selector 303 at its movable terminal Pm.

The signal selector 303, based on a control signal CTb from the shootingcontrol unit 60, connects the movable terminal Pm to any one of thethree terminals Pa, Pb, and Pc, to output the image signal DVc suppliedfrom the signal selector 302 through the selected terminal. The terminalPa of this signal selector 303 is connected to a signal input terminalof a random access memory (RAM) 304-1. The terminal Pb, on the otherhand, is connected to a signal input terminal of an RAM304-2 and theterminal Pc, to a signal input terminal of an RAM304-3.

The RAM304-1, based on a write control signal WT supplied from theshooting control unit 60, reads the image signal DVc output from theterminal Pa of the signal selector 303 and stores it. Further, theRAM304-1, based on a read control signal RT supplied from the shootingcontrol unit 60, read the stored image signal DVc and supplies it as animage signal DVm-1 to the terminal Pa of the signal selector 305 and theterminal Pa of the signal selector 306.

Similarly, the RAMs304-2 and 304-3 read the image signals DVc outputfrom the respective terminals Pb and Pc of the signal selectors 303 onthe basis of the write control signal WT supplied from the shootingcontrol unit 60 and store them. Further, the image signals DVc stored inthe RAMs304-2 and 304-3 are read on the basis of the read control signalRT supplied from the shooting control unit 60 and supplied as imagesignals DVm2 and DVm-3 to the terminals Pb and Pc of the signalselectors 305 and the terminals Pb and Pc of the signal selector 306,respectively.

The movable terminal Pm of the signal selector 305 is connected to theadder 301. This signal selector 305, based on a control signal CTc fromthe shooting control unit 60, switches the movable terminal Pm to anyone of the terminals Pa through Pc to select any one of the imagesignals DVm-1 through DVm-3 and supplies it as the image signal DVf tothe adder 301.

The movable terminal Pm of the signal selector 306 is connected to anoutput adjustment circuit 307. This signal selector 306, based on acontrol signal CTd from the shooting control unit 60, switches themovable terminal Pm to any one of the terminals Pa through Pc to selectany one of the image signals DVm-1 through DVm-3 and supplies it as animage signal DVh to the output adjustment circuit 307.

The output adjustment circuit 307, based on a control signal CTesupplied from the shooting control unit 60, adjusts a signal level ofthe image signal DVh according to the number of added frames andsupplies the output-signal-processing unit 41 with it as an image signalDVj having the predetermined output frame rate Fc in which the shotimages are contained at the variable frame rate. Further, for the imagesignal DVj, it generates a validity signal Tv indicating a frame of theimage having the variable frame rate and supplies it to an interfaceunit 42.

The frame rate conversion unit 35 converts a frame rate of the imagesignal DVb into a frame rate that matches a component connected for thepurpose of confirmation of shot images, for example, the electronicviewfinder 100 and supplies it as an image signal DVr to themonitor-signal-processing unit 51.

The output-signal-processing unit 41 performs process treatment such asγprocessing, profile compensation processing, and Knee correctionprocessing on the image signal DVj. Further, themotion-signal-processing unit 51 performs on the image signal DVrprocess treatment in accordance with the electronic viewfinder 100 etc.connected for confirmation of shot images. For example, in the case ofdisplaying an image to confirm a shot image using a CRT or an LCD, itperforms process treatment such as γ correction and gradation displaycorrection that matches the CRT or the LCD. By thus providing theoutput-signal-processing unit 41 and the motion-signal-processing unit51, process treatments for the image signals DVj and DVr can beperformed separately from each other.

An image signal DVk obtained by performing the process treatment at thisoutput-signal-processing unit 41 is supplied to an interface unit 42.Further, the motion-signal-processing unit 51 supplies a monitor signaloutput unit 52 with an image signal DVs obtained by performing theprocess treatment.

The interface unit 42 converts the image signal DVk into a signal CMoutthat matches a recording apparatus etc. to be connected to the videocamera. For example, in a case where an apparatus accommodating acomponent signal or an apparatus accommodating a composite signal is tobe connected, it converts the image signal DVk into signals that matchthese apparatuses respectively. Further, in a case where the imagesignal is transmitted through, for example, a serial digital interfacestandardized as SMPTE259M or SMPTE292M, it converts the image signal DVkinto a signal that conforms to the interface standards. Furthermore, theinterface unit 42 is provided with the validity signal Tv from theframe-addition-processing unit 30 as well as additional information MDfrom the shooting control unit 60, so that the interface unit 42provides the signal CMout with the validity signal Tv and the additionalinformation MD in a condition where they correspond to each of theframes in the image signal DVk and supplies this signal CMout to thesignal-recording device 70.

The monitor signal output unit 52 converts the supplied image signal DVsinto a signal EVout that matches the electronic viewfinder 100 providedfor confirmation of shot images and supplies it to the electronicviewfinder 100.

To the shooting control unit 60, an input unit 61 is connected, so thatthe shooting control unit 60 is supplied, from the input unit 61, with asignal in accordance with a user operation or a signal from a remotecontroller or an external apparatus etc. as operation signal PSc. Theshooting control unit 60, based on the operation signal PSc, generatesthe control signal CT etc., to control operations of the various units,thereby causing the shooting device to operate in accordance with theuser-operation signal or the signal from the remote controller or theexternal apparatus etc. Further, when supplied, as the operation signalPSc, with a frame rate setting signal PSF that sets a variable framerate, the shooting control unit 60 generates a control signal TC thatsets a shooting frame rate at the shooting unit 21 on the basis of theframe rate setting signal PSF and supplies it to the drive unit 62. Thisdrive unit 62, based on the control signal TC, generates a drive controlsignal RD and supplies it to the shooting unit 21, thereby causing theshooting unit 21 to output the image signal Spa having a shooting framerate on the basis of the frame rate setting signal PSF. Further, basedon the frame rate setting signal PSF, it generates the control signalsCTa, CTb, CTc, CTd, and CTe, and the write control signal WT and theread control signal RT and supplies them to theframe-addition-processing unit 30. By thus controlling the operations ofthe shooting unit 21 and the frame-addition-processing unit 30 on thebasis of the frame rate setting signal PSF, the shooting device 10 iscaused to generate an image signal having a predetermined output framerate in which shot images are contained at a set value of the variableframe rate.

Furthermore, the shooting control unit 60 generates information relevantto images having a variable frame rate, for example, the additionalinformation MD that indicates a shot date and time and imagingconditions and supplies it to the interface unit 42.

The following will describe operations of the shooting device 10. Thisshooting device 10 controls generation of an image signal at theshooting unit 21 so that the shooting unit 21 may generate the imagesignal Spa having a frame rate varied within a predetermined rangewithout changing a sampling frequency and switches the number of addframes at the frame-addition-processing unit 30 to thereby generate theimage signal DVj having a predetermined output frame rate.

In this case, to generate the image signal DVj having the variable framerate FRc, even if the variable frame rate FRc is supposed to be low, thenumber of add frames FAD at the frame-addition-processing unit 30 isswitched so that the shooting frame rate FRp which is a frame rate ofthe image signal Spa generated by the shooting unit 21 may fall in apredetermined range. Further, the number of add frames FAD is set sothat, for example, when the number of add frames FAD is switched, theshooting frame rate FRp may fall in the predetermined range and be highin value.

FIG. 4 is a flowchart for showing operations to set the number of addframes FAD and the shooting frame rate FRp in accordance with thevariable frame rate FRc. At step ST1, a switchover point of the numberof add frames and the number of add frames are set. In the setting, theshooting frame rate FRp is divided by a positive integer, so that aninteger value at which a quotient of this division turns integer(except 1) is set to the switchover point. This quotient is set to thenumber of add frames FAD. For example, if a maximum value of theshooting frame rate FRp is “60P (the numeral indicates the number offrames per second and P indicates the signal being of a progressivetype, which hold with the other cases)”, the set switchover points ofthe number of add frames and the numbers of add frames are (30P, 2frames), (20P, 3 frames), (15P, 4 frames), (12P, 5 frames), (2P, 30frames), (1P, 60 frames).

At step ST2, based on the switchover point of the number of add framesand the number of add frames set at step ST1, the process generatesaddition switchover information that indicates a relationship betweenthe variable frame rate FRc and the number of add frames. In this case,if the switchover point of the number of add frames and the number ofadd frames are set on the assumption that the maximum value of theshooting frame rate FRp is 60P, the addition switchover information isgenerated as shown in FIG. 5. That is, if the variable frame rate FRc is“60P≧FRc>30P”, the number of add frames FAD is set to “1”. If thevariable frame rate FRc is “30P≧FRc>20P”, the number of add frames FADis set to “2”. If the variable frame rate FRc is “20P≧FRc>15P”, thenumber of add frames FAD is set to “3”. Similarly, if the variable framerate FRc is “2P≧FRc>1P”, the number of add frames FAD is set to “30” andif the variable frame rate FRc is “FRc=1P”, the number of add frames FADis set to “60”.

At step ST3, the process determines the number of add frames thatcorresponds to a variable frame rate FRc, which is set by the user, onthe basis of the addition switchover information. For example, if theset variable frame rate FRc is “45P”, the number of add frames FAD is“1”. Further, if the set variable frame rate FRc is “14P”, the number ofadd frames FAD is “4”.

At step ST4, the process determines a shooting frame rate. In thisdetermination, the process multiplies the number of add frames FAD,which are determined at step ST3, and the set variable frame rate ERcand set a resultant product to the shooting frame rate FRp. For example,if the variable frame rate FRc is “45P”, the shooting frame rate FRp isset to “45P” because the number of add frames FAD is “1”. Further, ifthe variable frame rate FRc is “14P”, the shooting frame rate FRp is setto “56P” because the number of add frames FAD is “4”. Further, if thevariable frame rate FRc is varied, a variable range of the shootingframe rate FRp is on the side of the maximum value. For example, if thevariable frame rate FRc is varied in a range of “20P≧FRc>15P”, thevariable range of the shooting frame rate FRp becomes “60P≧FRp>45P”,which is on the side of the maximum value. Note here that in FIG. 5, therange of the shooting frame rate FRp with respect to the range of thevariable frame rate FRc is shown together with the addition switchoverinformation.

Thus, even if the variable frame rate FRc is varied within a range of“60P through 1P”, the number of add frames can be switched to controlthe shooting frame rate FRp into a range of “60P through 30P”. Further,a variable range of the shooting frame rate FRp with respect to eachnumber of add frames can be set to the side of a maximum value of theshooting frame rate FRp, so that it is possible to obtain the imagesignal DVj having a desired output frame rate on the basis of an imagesignal Spa of more speedily shot images.

The shooting control unit 60 performs the above-mentioned processing ofFIG. 4 to determine the shooting frame rate FRp and the number of addframes FAD for a variable frame rate FRc which is set by the frame ratesetting signal PSF from the input unit 61.

Note here that in a case where the variable frame rate FRc of the imagesignal DVj is set in a range of “60P≧FRc>30P” on the basis of the framerate setting signal PSF, to output the signal CMout generated on thebasis of this image signal DVj from the shooting device, the shootingcontrol unit 60 controls the frame-addition-processing unit 30 to setthe number of add frames FAD to “1”. Further, it controls operations ofthe drive unit 62 so that the drive unit 62 may supply the shooting unit21 with the drive control signal RD that is the shooting frame rate FRpof the image signal Spa output from the shooting unit 21 multiplied byan FAD of the variable frame rate.

Further, in a case where the variable frame rate FRc is set in a rangeof “30P≧FRc>20p” on the basis of the frame rate setting signal PSF, theshooting control unit 60 controls the frame rate addition processingportion 30 to set the number of add frames FAD to “2”. Further, theshooting control unit 60 controls the operations of the drive unit 62 sothat the drive unit 62 may supply the shooting unit 21 with the drivecontrol signal RD that is the shooting frame rate FRp of the imagesignal Spa output from the shooting unit 21 multiplied by an FAD (twiceas large) of the variable frame rate FRc. In this case, two frames ofthe image signal having the shooting frame rate are added to generatethe image signal DVj, so that the image signal DVj has a desired outputframe rate. Further, since the shooting frame rate FRp comes in a rangeof “60P≧FRp>40P”, the shooting frame rate can be controlled into therange of “60P≧FRp>30P”.

Similarly, to set the variable frame rate FRc in a range of“15P≧FRc>12P”, the shooting control unit 60 controls theframe-addition-processing unit 30 to set the number of add frames FAD to“4”. Further, the shooting control unit 60 controls the operations ofthe drive unit 62 so that the drive unit 62 may supply the shooting unit21 with the drive control signal RD that is the shooting frame rate FRpof the image signal Spa output from the shooting unit 21 by an FAD(fourfold) of the variable frame rate FRc. In this case, four frames ofthe image signal having the shooting frame rate are added to generatethe image signal DVj, so that the image signal DVj has a desired outputframe rate. In this case, the shooting frame rate comes in a range of“60P≧FRp>40P”, so that the shooting frame rate can be controlled into arange of “60p≧FRp>30P”.

Similarly, by varying the shooting frame rate FRp of the image signalSpa generated by the shooting unit 21 and the number of add frames FADat the frame-addition-processing unit 30, it is possible to obtain theimage signal DVj having a desired variable frame rate FRc. Note herethat by holding beforehand the table of FIG. 5 concerning the additionswitchover information and the shooting frame rate, it is of courseunnecessary to perform processing of the flowchart shown in FIG. 4 eachtime the variable frame rate FRc is switched.

The following will describe varying operation of the shooting frame rateFRp of the image signal Spa generated by the shooting unit 21. FIG. 6shows an outlined configuration of a frame interline transfer (FIT)-typeCCD as an example of the image pickup device used in the shooting unit21. An shooting region 211 a of a CCD210 has a matrix of photoelectrictransfer devices 212 and vertical transfer registers 214 each of whichis used to transfer to an accumulation region 211 b a shot chargesupplied from each of the photoelectric transfer devices 212 via asensor gate 213. The vertical transfer registers 214 are provided asmany as a number that is supposed to correspond to the number of pixelsper line. The number of transfer steps of each of the vertical transferregisters 214 corresponds to the number of scanning lines.

The accumulation region 211 b of the CCD210 is used to accumulate shotcharges of, for example, pixels of one frame and constituted of verticaltransfer registers 215 having a configuration similar to that of thevertical transfer registers 214 of the shooting region 211 a.

Further, the shooting unit 21 has a horizontal transfer register 216 anda signal output circuit 217 connected to an output terminal side of thehorizontal transfer register 216. The number of transfer stages of thehorizontal transfer register 216 is supposed to correspond to the numberof pixels per line. Further, the signal output circuit 217 converts shotcharges supplied from the horizontal transfer register 216 into avoltage signal and output it.

The shooting unit 21 having such a configuration is controlled inoperation when it is supplied, from the drive unit 71, with a variety oftiming signals such as a sensor gate pulse for opening each of thesensor gates 213, a vertical transfer clock pulse for driving thevertical transfer register 214, a vertical transfer clock pulse fordriving the vertical transfer register 215 of the accumulation region212 b, and a horizontal transfer clock pulse for driving the horizontaltransfer register 216, as drive control signal RC.

The shot charge generated by the photoelectric transfer device 212 ofthe shooting region 211 a is read by each of the vertical transferregisters 214 via the sensor gate 213 during a vertical blankinginterval and the shot charge thus read is transferred to the verticaltransfer register 215 of the accumulation region 211 b at a high speedto be accumulated. Then, the shot charges accumulated in theaccumulation region 211 b are read to the horizontal transfer register216 by as much as one line during a horizontal blanking interval andtransferred to the signal output circuit 217 sequentially. The signaloutput circuit 217 converts the supplied shot charges into a voltagesignal and outputs it. It is thus possible to obtain image signal of oneline from the signal output circuit 217. During the next horizontalscanning time also, the same processing can be performed to obtain theimage signal of next one line from the signal output circuit 217.Similarly, the image signal of one frame can be obtained.

Then, signals of the vertical transfer registers 214 can be flushedduring the vertical blanking interval to reduce smears and the shotcharges generated by the photoelectric transfer device 212 can be readvia the sensor gate 213 to the vertical transfer registers 214 toperform the above-mentioned processing, thereby generating the imagesignal Spa.

Note here that the image pickup device used in the shooting unit 21 isnot limited to a frame interline transfer (FIT) type CCD but may be aninterline transfer (IT) type CCD etc.

In the case of varying the shooting frame rate FRp of the image signalSpa, the drive control signal RD supplied from the drive unit 62 to theshooting unit 21 can be used to control a charge accumulation period, animaging charge read timing, etc. at the CCD210, thereby obtaining theimage signal Spa having a varied frame rate. Furthermore, if theshooting frame rate FRp is varied using a common data rate system (CDRsystem: common sampling frequency system), it is possible to generatesuch an image signal Spa that an image size during a valid screen periodmay not change even if the shooting frame rate FRp is varied. Further,by using the CDR system, the configuration is made simple because it isunnecessary to vary an operating frequency of each unit that uses theshooting frame rate FRp, in accordance with the shooting frame rate FRp.

According to this CDR system, by adjusting duration of a horizontalblanking interval as shown in FIG. 7B or that of a vertical blankinginterval as shown in FIG. 7C for an image signal whose blanking intervaland valid screen period have been set as shown in FIG. 7A, it ispossible to generate an image signal having a varied shooting frame rateFRp without changing the image size during the valid screen period.

FIGS. 8A-8H and 8J-8N are diagrams for explaining operations in the caseof adjusting duration of the horizontal blanking interval and FIG. 9A-9Gare diagrams for explaining operations in the case of adjusting durationof the vertical blanking interval. FIG. 8A shows an exposure startingtiming TMs and FIG. 8B, an exposure ending timing TMe. An interval ofthe exposure starting timing TMs and that of the exposure ending timingTMe are equal to a frame period of the shooting frame rate FRp, while aperiod from the exposure ending timing to the next exposure startingtiming corresponds to the vertical blanking interval V.BLK as shown inFIG. 8C. Further, a period from the exposure starting timing to the nextexposure ending timing makes up an exposure period.

Shot charge generated at the photoelectric transfer device 212 during anexposure period is read to the vertical transfer register 215 shown inFIG. 6 during the next vertical blanking interval as shown in FIG. 8D.

The charges read to the vertical transfer registers 215 are read foreach line to the horizontal transfer registers 216 with respect to eachread starting pulse of a horizontal read starting signal TMh shown inFIG. 8G and supplied to the signal output circuit 217 sequentially at asampling frequency, to generate a signal of one line for the validscreen period in the image signal Spa such as shown in FIG. 8E. Notehere that FIG. 8F shows a vertical synchronization signal VD.

FIGS. 8H, 8J, and 8K show portions of a frame period, of which FIG. 8Hshows a horizontal synchronization signal and FIG. 8J shows thehorizontal read starting signal TMh, which provides a reference forgeneration of a signal of one line for the valid screen period asdescribed above. Note here that a period from a synchronization pulse ofthe horizontal synchronization signal HD to a read starting pulse of thehorizontal read starting signal TMh corresponds to a horizontal blankinginterval H, BLK in the image signal Spa shown in FIG. 8K, while a periodfrom a read starting pulse of the horizontal read starting signal TMh toa synchronization pulse of the next horizontal synchronization signal HDprovides a valid screen period.

FIGS. 8L-8N show signal portions when the shooting frame rate FRp ishigh, of which FIG. 8N shows the horizontal synchronization signal HDand FIG. 8M shows the horizontal read starting signal TMh. In this case,if the horizontal blanking interval H.BLK, which is a period from asynchronization pulse of the horizontal synchronization signal HD to aread starting pulse of the horizontal read starting signal TMh, ischanged from such as shown in FIG. 8K into a shorter one such as shownin FIG. 8L, an interval of the horizontal synchronization signal HD isreduced to increase the shooting frame rate FRp. Further, a period ismade constant from a read starting pulse of the horizontal read startingsignal HD to a synchronization pulse of the next horizontalsynchronization signal HD. That is, by making constant the samplingfrequency and the number of pixels during the valid screen period, it ispossible to generate such a CDR-system image signal Spa shown in FIG. 8Kor 8L that the valid screen period may be constant irrespective of theshooting frame rate FRp. Note here that FIGS. 8A-8H, FIG. 8J and FIG. 8Kshow the number of lines and the number of samples in the case of “48P”when the valid screen period is 1920 samples×1080 lines, while FIGS.8L-8N show the number of lines and the number of samples in the case of“60P” when the valid screen period is 1920 samples×1080 lines.

The following will describe operations in the case of adjusting theduration of the vertical blanking interval with reference to FIGS.9A-9G. Note here that FIGS. 9A-9D correspond to FIGS. 8A-8Drespectively.

Charges read to the vertical transfer registers 215 are read for eachline to the horizontal transfer registers 216 with respect to each readstarting pulse of the horizontal read starting signal TMh shown in FIG.9G and the shot charges thus read are then supplied to the signal outputcircuit 217 sequentially, to generate the image signal Spa as shown inFIG. 9E. In this case, the vertical blanking interval V.BLK is adjustedwhich is a period from a synchronization pulse of the verticalsynchronization signal VD shown in FIG. 9F to a read starting pulse of afirst horizontal read starting signal TMh for each of the frames shownin FIG. 9G. Further, by making constant a period from a read startingpulse of the first horizontal read starting signal TMh to asynchronization pulse of the vertical synchronization signal VD, it ispossible to generate such a CDR-system image signal Spa shown in FIG. 9Ethat the valid screen period is made constant irrespective of theshooting frame rate FRp.

In such a manner, by making constant the sampling frequency and thenumber of pixels during the valid screen period and making variable thehorizontal and vertical blanking intervals in accordance with theshooting frame rate FRp, it is possible to generate such an image signalSpa that the valid screen period may be constant and the image size maynot change even if the shooting frame rate FRp is varied. Note here thatif, for example, the vertical blanking interval is prolonged inaccordance with the shooting frame rate FRp, an interval until the nextframe image is displayed is prolonged so that flickering may beconspicuous. Therefore, it is desirable to adjust the horizontalblanking interval in accordance with the shooting frame rate FRp.

The following will describe an operation of frame addition performed inthe frame-addition-processing unit 30. FIG. 10 is a flowchart forshowing the frame addition operation.

At step ST11, the process performs initial setting. In this initialsetting, the process specifies any one of the RAMs304-1 through 304-3 asa write RAM in which the image signal DVc is written. This write RAM canbe specified by switching the movable terminal Pm of the signal selector303 using the control signal CTh. Further, an external readability flagis provided which indicates whether frames have been added completely asmany as the number of add frames FAD and set to an OFF state indicatingthat frame addition processing has not yet completed.

At step ST12, the process supplies a write control signal WTa to thewrite RAM to start writing the image signal DVc to the write RAM.

At step ST13, the process read accommodation processing. This readaccommodation processing is performed to output an image signal at thevariable frame rate FRc, so that if frame addition has completed, theprocess generates and outputs an image signal having the variable framerate FRc on the basis of a signal obtained by the frame addition. If theframe addition has not yet completed, on the other hand, the processprovides a blank frame.

FIG. 11 is a flowchart for showing read accommodation processing. Atstep ST31, the process decides whether a synchronization pulse isdetected in an external reading vertical synchronization signal VDchaving the variable frame rate FRc. If the synchronization pulse isdetected in the vertical synchronization signal VDc, the process goes tostep ST32 and, otherwise, goes to step ST34.

At step ST32, the process decides whether the external readability flagis set ON. If the external readability flag is not set ON, the processprovides a blank frame and goes to step ST34 because no signal isreceived which indicates that frames as many as the number of add framesFAD are added completely. If the external readability flag is set ON, onthe other hand, the process goes to step ST33, where the process startsreading the signal from a later-described external read RAM to which thesignal indicating completion of addition of frames as many as the numberof add frames FAD has been written and goes to step ST34. Further, theprocess regards a frame of the signal read from the external read RAM tobe that of an image having the variable frame rate and “validates” thevalidity signal Tv for this frame.

At step ST34, the process decides whether a condition is met to set OFFthe external readability flag. If, in this case, the signal of one framehas been read completely from the external read RAM, the process decidesthe set-OFF condition of the external readability flag is met and goesto step ST35. If the signal of one frame is not read completely from theexternal read RAM or the signal is not read or the external readabilityflag is set OFF, on the other hand, the process ends the readaccommodation processing. At step ST35, the process set OFF the externalreadability flag. Further, when it has set OFF the external readabilityflag, the process releases specification of the external read RAM andends the read accommodation processing. Furthermore, the processswitches the validity signal Tv from being “valid” to “invalid”.

At step ST14, the process decides whether the signal of one frame hasbeen written completely to the write RAM. If the signal of one frame isyet to be written completely, the process returns to step ST13 and,otherwise, goes to step ST15.

At step ST15, the process decides whether frames have been addedcompletely as many as the number of add frames FAD. If, in this case,frames as many as the number of add frames FAD are yet to be addedcompletely, the process goes to step ST16 and, otherwise, goes to stepST20.

At step ST16, the process performs first RAM switchover. In this firstRAM switchover processing, the write RAM is switched to specify anyother unspecified RAM as the write RAM. Further, an RAM specified as thewrite RAM before the switchover is specified as an internal read RAM.Furthermore, pre-switchover specification of an internal read RAM isreleased.

At step ST17, the process starts processing to add up the input imagesignal DVc and a signal written in the internal read RAM and write 2 itto the write RAM and goes to step ST18. At step ST18, the processperforms the above-mentioned read accommodation processing and goes tostep ST19.

At step ST19, the process decides whether the signal of one frame hasbeen written completely to the write RAM. If, in this case, the signalof one frame is yet to be written completely, the process returns tostep ST18 and, otherwise, returns to step ST15.

At step ST15, if the process decides frames have been added completelyas many as the number of add frames FAD and goes to step ST20, theprocess performs second RAM switchover processing at step ST20. In thesecond RAM switchover, the process switches the write RAM and specifiesany other unspecified RAM to the write RAM. Further, the processspecifies the pre-switchover write RAM to an external read RAM.Furthermore, the process releases specification of the pre-switchoverinternal read RAM. Further, since the frames as many as the number ofadd frames FAD have been added completely, the process sets ON theexternal readability flag and returns to step ST12.

When the frames as many as the number of add frames have thus been addedcompletely by switching the write RAM and internal read RAM whilewriting the signal, the process specifies the write RAM as the externalread RAM and sets ON the external readability flag. Further, the processdetects a state of the external readability flag during writing of thesignal, to cause a signal indicating completion of addition of frames asmany as the number of add frames FAD to be output at the variable framerate FRc. Furthermore, the process “validates” the validity signal Tvfor a frame of a signal read from the external read RAM.

FIGS. 12A-12G and FIGS. 13A-13E show operations in the case ofgenerating such an image signal DVj that the variable frame rate FRc is,for example, “18P” and the output frame rate Fc is “60P”. Of these, FIG.12A shows the image signal DVb, FIG. 12B shows an operation of theRAM304-1, FIG. 12C shows that of the RAM304-2, FIG. 12D shows that ofthe RAM304-3, FIG. 12E shows the external readability flag, FIG. 12Fshows the image signal DVj, and FIG. 12G shows the validity signal Tv.

If the variable frame rate FRc is “18P”, based on FIG. 5, the number ofadd frames FAD is “3”, the shooting frame rate FRp is “54P”, which isthree times the variable frame rate FRc, and the image signal DVb has aframe rate of “54P”.

At time point t1 of FIGS. 12A-12G when frame “0f” of the image signalDVb starts, the shooting control unit 60, as shown in FIG. 13A, sets themovable terminal Pm of the signal selector 302 of theframe-addition-processing unit 30 to the side of the terminal Pa andalso sets the movable terminal Pm of the signal selector 303 to the sidethe terminal Pa, to specify the RAM304-1 as a write RAM. In this case,an image signal of frame “0f” is supplied to the RAM304-1, which is thewrite RAM. Further, the shooting control unit 60 supplies the writecontrol signal WT to the RAM304-1 so that the RAM304-1 may store theimage signal of frame “0f”.

Then, when an image signal of frame “1f” at time point t2 starts, theshooting control unit 60 sets the movable terminal Pm of the signalselector 305 to the side of the terminal Pa as shown in FIG. 13B.Further, it supplies the read control signal RT to the RAM304-1 to readthe stored image signal of frame “0f”. In this case, the adder 301 issupplied with the image signal DVb of frame “1f” and the image signal offrame “0f” read from the RAM304-1 as the image signal DVf. Therefore,the adder 301 adds the image signal of frame “0f” and that of frame “1f”to generate an added-up signal DVg. Further, the shooting control unit60 switches the write RAM to set the movable terminal Pm of the signalselector 302 to the side of the terminal Pb and the movable terminal Pmof the signal selector 303 to the side of the terminal Pb, to specifythe RAM304-2 as a write RAM and supply the added-up signal DVg to theRAM304-2. Further, the shooting control unit 60 supplies the RAM304-2with the write control signal WT, thus causing the RAM304-3 to store theadded DVg obtained as a result of adding up the image signals of frames“0f” and “1f”.

When the image signal DVb of frame “2f” starts at time point t3, theshooting control unit 60, to generate a three-frame added-up signal,sets the movable terminal Pm of the signal selector 305 to the side ofthe terminal Pb connected to the RAM304-2 in which the added-up signalis stored, as shown in FIG. 13C. Further, it supplies the read controlsignal RT to the RAM304-2 to read the stored added-up signal for frames“0f” and “1f”. In this case, the adder 301 is supplied with the imagesignal DVb of frame “2f” and an added-up signal read from the RAM304-2as the mage signal DVf. Therefore, the adder 301 generates an added-upsignal DVg obtained by adding up the image signals of frames “0f”through “2f”. Further, the shooting control unit 60 switches the writeRAM to set the movable terminal Pm of the signal selector 302 to theside of the terminal Pb and the movable terminal Pm of the signalselector 303 to the side of the terminal Pc, to specify the RAM304-3 asa write RAM and supply the added-up signal DVg to the RAM304-3.Furthermore, the shooting control unit 60 supplies the RAM304-1 with thewrite control signal WT, causing the RAM304-3 to store the added-upsignal DVg for frames “0f” through “2f”.

When the image signal DVb of frame “3f” starts at time point t4, theadded-up signal for the number of add frames has been written to theRAM304-3 completely, so that the external readability flag is set ON asshown in FIG. 12E. Further, the RAM304-3 is specified as an externalread RAM. Since the added-up signal for the number of add frames, thatis, the added-up signal obtained by adding up the image signals DVb forthe three frames has been generated completely, the shooting controlunit 60, as shown in FIG. 13D, sets the movable terminal Pm of thesignal selector 302 to the side of the terminal Pa and the movableterminal Pm of the signal selector 303 to the side of the terminal Pa.In this case, the image signal DVb of frame “3f” is supplied to theRAM304-1. Further, the shooting control unit 60 supplies the RAM304-1with the write control signal WT, thereby causing the RAM304-1 to storethe image signal of frame “3f”.

Next, in a case where a timing comes to start a frame of the imagesignal DVj when an added-up signal for the number of add frames has beenwritten completely to the RAM304, for example, in a case where a timingcomes to start an output frame of the image signal DVj at time point t5when the added-up signal DVg obtained by adding up the image signals offrames “0f” through “2f” has been written completely to the RAM304-3,the shooting control unit 60, as shown in FIG. 13E, sets the movableterminal Pm of the signal selector 306 to the side of the terminal Pcconnected to the RAM304-3 specified as the external read RAM. Further,the shooting control unit 60 supplies the RAM304-3 with the read controlsignal RT to read the stored added-up signal obtained by adding up theimage signals for the three frames and supply it as the image signal DVhto the output adjustment circuit 307.

The output adjustment circuit 307 adjusts a signal level of the imagesignal DVh on the basis of the control signal CTe from the shootingcontrol unit 60. That is, since the image signal DVh is an added-upsignal obtained by adding up the image signals for the three frames, ita multiplies the signal level of the image signal DVh by “⅓”, therebysetting the image signal DVh to a signal having a predetermined levelrange. Furthermore, the validity signal Tv indicating a frame of animage having the variable frame rate is “validated” and, if it is noframe of an image having the variable frame rate, it is “invalidated” asshown in FIG. 12G. Note here that in FIGS. 14G and 15G also, if it is aframe of an image having the variable frame rate, the signal is shows asbeing “valid” and, otherwise, the signal is shown as being “invalid”.

Similarly, the shooting control unit 60 can use the RAMs304-1 through304-3 to generate an added-up signal by adding up three frames of theimage signal DVb and read this added-up signal at a timing to start aframe of the image signal DVj, thereby generating an image signal havinga predetermined output frame rate in which a shot image is contained ata variable frame rate.

Next, at time point t6 when a frame in which the signal has been readfrom the RAM304-3 ends, the external readability flag is set OFF. Notehere that if a period in which no signal is read from the external readRAM, for example, a period from time point t6 to time point t7 is usedas a blank frame without image, when an image is displayed on the basisof the image signal DVj, its brightness may flicker. Therefore, in aperiod “invalidated” by the validity signal Tv, an image of “validated”frames “(0f+1f+2f)/3” can be displayed repeatedly to prevent flickeringof the brightness.

Furthermore, by employing the CDR system at theframe-addition-processing unit 30, it is possible to store a signal of avalid screen period in the RAM304 and read this stored signal at afrequency equal to that at the time of writing and, furthermore, adjusta blanking interval, thereby outputting such an image signal having anoutput frame rate that an image size in the valid screen period may bethe same irrespective of the variable frame rate even if the suppliedimage signal DVb is not of the CDR system. Further, theframe-addition-processing unit 30 may adjust the signal level of theimage signal DVb in accordance with the number of add frames previously,and then executes frame addition processing. In this case, a bit widthof a signal, which is stored in the RAM or subject to the additionprocessing, is reduced, so that a configuration of theframe-addition-processing unit 30 can be simplified as compared to acase where the signal level of the image signal DVh is adjusted at theoutput adjustment circuit 307.

Note here that the variable frame rate FRc may vary during shooting inorder to obtain special video effects. Operations for altering thevariable frame rate during shooting will be described as follows.

The variable frame rate varies either in a case where image signals havebeen added up as described above or in a case where they have not. Asshown in, for example, FIG. 5, to control the variable frame rate FRcinto a range of “60P≧FRc>30P”, it is unnecessary to perform frameaddition processing, while to control the variable frame rate FRc into arange of not larger than “30P”, frame addition processing is performed.Therefore, the shooting control unit 60 executes different processing,depending on whether the frame addition processing is performed or not.

FIGS. 14A-14G show a case where frame addition processing is notperformed, for example, a case where the variable frame rate is alteredfrom “60P” to “48P”. In this case, the shooting control unit 60 switchesthe shooting frame rate FRp after a frame of the image signal DVb iscompleted. Further, the RAMs304-1 through 304-3 are sequentially used tostore an image signal of one frame in each of these RAMs and, at a framestarting timing for the image signal DVj in a period when none of thestored signals is being read, those stored image signals are read at thevariable frame rate FRc and output.

For example, when the output frame rate is altered from “48P” to “60P”by the frame rate setting signal PSF which is shown in FIG. 14A frominput unit 61 at time point t11, the shooting control unit 60 controlsthe shooting unit 21 through the drive unit 62, to switch the shootingframe rate FRp at time point t12 when the frame of the image signal DVbis completed as shown in FIG. 14B. Further, the shooting control unit 60stores each frame of the image signal DVb shown in this FIG. 14B in eachof the RAMs304-1 through 304-3 sequentially as shown in FIGS. 14C, 14D,and 14E. Further, after the image signal of one frame is stored in eachof the RAMs304, at frame starting timings for the image signal DVj, forexample, at time points t21, t22, and t23 in a period when none of thesestored signals is being read, the signal stored in each of the RAMs isread. Further, if the image signals stored in the RAMs304-1 through304-3 are read already as shown at time point t24, their frames areinvalidated by the validity signal Tv as shown in FIG. 14G, so that animage of a validated frame “8f” is used repeatedly. By performing theprocessing in such a manner, it is possible to obtain the image signalDVj having a desired output frame rate “60P” in which a shot image iscontained at a variable frame rate “48P”.

The following will describe a case where the frame addition processingis performed, with reference to FIGS. 15A-15G. FIGS. 15A-15G show a casewhere the variable frame rate FRc is altered, for example, from “31P” to“30P”, “29P”, and “28P” sequentially. In this case, the shooting controlunit 60 is supposed to alter the shooting frame rate FRp and the numberof add frames FAD after it has obtained an added-up signal obtained byadding up image signals as many as the number of add frames.

When, for example, the variable frame rate FRc is altered from “31P” to“30P” at time point t31 by the frame rate setting signal PSF shown inFIG. 15A from the input unit 61, the shooting control unit 60 controlsthe shooting unit 21 via the drive unit 62 to switch the shooting framerate FRp at a moment when a frame of the image signal DVb is completedas shown in FIG. 15B. Note here that as shown in FIG. 5, the shootingframe rate FRp is “31P” when the variable frame rate FRc is “31P” andthe shooting frame rate FRp is “60P” when the variable frame rate FRc is“30P”. Therefore, the shooting control unit 60 switches the shootingframe rate FRp from “31P” to “60P” at time point t32 when the frame ofthe image signal DVb is completed. Further, the shooting control unit60, as shown in FIG. 15C for example, causes the RAM304-1 to store theimage signal DVb of frame “1f” at the time when the shooting frame rateFRp is “31P”. Furthermore, since the variable frame rate FRc has beenaltered from “31P” to “30P”, the number of add frames FAD is alteredfrom “1” to “2”. Therefore, the shooting control unit 60 controlsoperations of the frame-addition-processing unit 30 to add up the imagesignals DVb of two frames, thereby generating an added-up signal andoutputting this added-up signal as the image signal DVj.

When the variable frame rate FRc is altered from “30P” to “29P” at timepoint t33, a frame of the corresponding image signal DVb is completed attime point t34. However, at time point t34, the processing of adding upthe image signal of the two frames has not yet completed. Therefore, theshooting control unit 60 switches the shooting frame rate FRp from “60P”to “58P” when a frame next to the completely added up the image signalof two frames is completed, that is, at time point t35. In such amanner, after the frame adding-up processing is completed, the shootingframe rate FRp is altered, so that as shown in FIG. 15F, the imagesignal DVj becomes an image signal having a predetermined output framein which a shot image having a variable frame rate set by the input unit61 is contained. Further, the validity signal Tv becomes such as shownin FIG. 15G.

In such a manner, there is provided an shooting device that has theshooting unit for generating an image signal having an shooting framerate from a shot image, the frame-addition-processing unit for adding upframes on the basis of an image signal generated by the shooting unitand outputting an image signal having a predetermined output frame ratein which the shot image is contained at the variable frame rate togetherwith the validity signal indicating a frame of an image having thevariable frame rate in the image signal having this output frame rate,and the shooting control unit for controlling operations of the shootingunit and the frame-addition-processing unit based on the frame ratesetting signal and switching the number of add frames in varying of theshooting frame rate and/or adding of frames to set the variable framerate to a frame rate based on the frame rate setting signal.Alternatively, an image signal having an shooting frame rate isgenerated from the shot image, based on which generated image signalframes are added up, so that an image signal having a predeterminedoutput frame in which the shot image is contained at the variable framerate is output together with the validity signal indicating a frame ofthe image having the variable frame rate in the image signal having thisoutput frame rate, to switch the number of add frames in varying of theshooting frame rate and/or adding up of frames on the basis of the framerate setting signal, thereby setting the variable frame rate to a framerate based on the frame rate setting signal.

Therefore, if, as described later, a signal validated by the validitysignal Tv is selected from among image signals obtained by shootingimages at various variable frame rates and recorded at a recording framerate in a recording medium, when reproducing this recording medium at adesired frame rate, a signal capable of providing a variable-speedplayback image that matches the variable frame rate is recorded in therecording medium, so that without recording the image signal in a serveretc. and then performing image processing, it is possible to simplyconfirm the special video effects speedily only by reproducing thesignal recorded in the recording medium at a desired frame rate.Further, by selecting images validated by the validity signal andrecording them, it is possible, for example, to use a server etc. nothaving a large recording capacity.

That is, to easily obtain special video effects such as high-speedplayback or slow-motion playback, it is possible to shoot images at, forexample, a frame rate lower than a predetermined one by using aconventional shooting device that can vary a frame rate during shootingand reproduce them at the predetermined frame rate, thereby easilyobtaining a high-speed playback image. By shooting images at a higherframe rate and reproducing them at the predetermined frame rate, on theother hand, a slow-motion playback image can be obtained easily. Notehere that in a case where an image signal output from the conventionalshooting device is recorded, if a recording frame rate of the recordingdevice is constant, an image signal is generated in such a manner thatvalid picture frames as many as a number that corresponds to an shootingframe rate when shooting may be contained in the image signal havingthis recording frame rate. Therefore, if an image signal output from theshooting device is recorded at a recording frame rate, it is impossibleto efficiently record only a signal having a required valid pictureframe rate. However, efficient recording is possible by selecting imagesvalidated by the validity signal output from the shooting device 10 ofthe present embodiment and recording these images.

Furthermore, the shooting control unit in the shooting device generatesadditional information relevant to images each having the variable framerate and outputs it together with an image signal having a predeterminedoutput frame rate. Alternatively, it generates additional informationrelevant to images each having the variable frame rate and outputs ittogether with an image signal having a predetermined output frame rateso that shooting conditions etc. can be confirmed easily on the basis ofthis additional information. Further, the shooting control unit controlsthe shooting unit to generate a shoot signal of the common data rate(CDR) system. Alternatively, it can generate a shoot signal of the CDRsystem as an image signal to keep constant an image size during a validscreen period even when the variable frame rate is changed.

Next, a configuration of the signal-recording device 70 is shown in FIG.16. Note here that FIG. 16 shows it together with a demodulation unitand an image decompression unit to be used in a reproduction tolater-describe an operation of reproducing a signal recorded in therecording medium.

The signal CMout output from the shooting device 10 is supplied to theinterface unit 71 in the signal-recording device 70. The interface unit71 separates the image signal DVk, the additional information MD, andthe validity signal Tv from the signal CMout and supplies the imagesignal DVk to an image compression unit 72. Further, it supplies theadditional information MD and the validity signal Tv to astorage-processing unit 73.

The image compression unit 72 performs compression processing to reducea signal quantity of the image signal DVk. In this compressionprocessing, as described later, a signal of a frame validated by thevalidity signal Tv is selected to perform intra-frame predictiveencoding, thereby generating an encoded signal DQa. This generatedencoded signal DQa is supplied to the storage-processing unit1111 73.

The storage-processing unit 73 selects an encoded signal DQw of an imagevalidated by the validity signal Tv from among the encoded signals DQaand stores it. Further, it stores the additional information MDwrelevant to a stored image. Further, it reads the stored encoded signalDQw and additional information MDw and supplies them to a modulationunit 74.

FIG. 17 is a diagram for showing a configuration of thestorage-processing unit 73. To a data-conversion-processing circuit 731,an image memory 732 for storing the encoded signal DQW and a data memory733 for storing the additional information MDw are connected. Further,to the image memory 732 and the data memory 733, a memory controlcircuit 734 for controlling signal write/read operations is connected.

The data-conversion-processing circuit 731 converts the encoded signalDQw into a signal ME in a format that matches the image memory 732 andsupplies it to the image memory 732. In this case, the encoded signalDQw obtained through compression processing has a different signalquantity with different image contents and the signal quantity of thesignal ME varies with each frame, so that when this signal ME is writtento the image memory 732, it is impossible to easily read the signal MEfor each frame image. Therefore, to enable the signal ME to be easilyread for each frame image unit from the image memory 732, thedata-conversion-processing circuit 731 equalizes a signal quantity ofthe signal ME for each frame. That is, the image compression portion 72performs compression processing so that the signal quantity of theencoded signal DQa for each frame may not exceed a preset signalquantity. Further, if the signal quantity of the signal ME is less thanthat when the signal ME is generated on the basis of the encoded signalDQw having a preset signal quantity, the data conversion processingcircuit 731 utilizes, for example, an invalid signal and writes it tothe image memory 732 as a signal ME having a constant signal quantity.

Further, the data-conversion-processing circuit 731 removes from thesignal ME read from the image memory 732 an invalid signal added to makethe signal ME have a constant signal quantity and recovers it to asignal DQw having an original format and supplies it to the modulationunit 74 shown in FIG. 16. Similarly, it converts the additionalinformation MDw into the signal MF having a format that matches the datamemory 733 and supplies it to the data memory 733. Further, it recoversthe signal MF read from the data memory 733 to the additionalinformation MDw having an original format and supplies it to themodulation unit 74 shown in FIG. 16.

The memory control circuit 734 generates write control signals WCv andWCm and read control signals RCv and RCm on the basis of the validitysignal Tv supplied from the interface unit 71 and a control signal CUasupplied from a recording control unit 80. It supplies these writecontrol signal WCv and read control signal RCv to the image memory 732to write to the image memory 732 the signal ME on the basis of an imagevalidated by the validity signal Tv. Further, it reads the writtensignal ME in an order they have been written when a quantity of signalsstored in the image memory 732, that is, a signal quantity of signalsthat have been written in the image memory 732 but has not yet readreaches a predetermined level.

Furthermore, it supplies the write control signal WCm and the readcontrol signal RCm to the data memory 733 to write to the data memory733 a signal MF of the additional information MDw that corresponds to aframe image written to the image memory 732. To read the signal MF fromthe image memory 732, the signal MF of the additional information MDwthat corresponds to a signal of a frame image is read.

Further in the memory control circuit 734, as information that indicatesa quantity of signals stored in the image memory 732, phase differenceinformation AP indicating a difference in phase between a write positionand a read position for the signal on, for example, the image memory 732is supplied to the recording control portion 80. This phase differenceindicates an address distance between the write position and the readposition or the number of frames between them.

The modulation unit 74 shown in FIG. 16 adds an error correcting code tothe encoded signal DQw and the additional information MDw and performschannel coding that matches the recording medium to generate a recordingsignal Sw having a predetermined recording format and supply it to ahead portion 75. Based on this recording signal Sw, it drives the headportion 75 to record the shot image and the additional information inthe recording medium 90 at a predetermined recording frame rate. Notehere that as the head portion 75, such a head portion as to match therecording medium 90 is used. For example, to use a magnetic tape as therecording medium or an optical disc, a magnetic head or an opticalpickup is used respectively.

A reproduction signal Sr obtained by reproducing the recording medium 90at the head portion 75 is supplied to a demodulation unit 76. Thedemodulation unit 76 performs demodulation processing or errorcorrecting processing on the reproduction signal Sr to supply anobtained encoded signal DQr to an image compression unit 77. Further, itoutputs additional information MDr obtained at the modulation unit 76from the signal-recording device 70. The image decompression portion 77performs decompression processing on the encoded signal DQr to generatethe image signal MTout and supply it to the image display device 110.Note here that the image compression unit 72 and the image decompressionunit 77 are provided to efficiently record the image signal DVk in therecording medium 90 and are not always necessary to constitute thesignal-recording device 70.

To the recording control unit 80, an input unit 81 is connected, so thata signal in accordance with user operations or a signal from a remotecontroller or an external apparatus etc. is supplied as an operationsignal Psv through the input unit 61 to the shooting control unit 60.The recording control unit 80 generates a control signal CU etc. on thebasis of the operation signal PSv to control operations of the variousunits, thereby causing the signal-recording device to operate inaccordance with the user operations or a signal from the remotecontroller or the external apparatus etc.

Further, in a case where an operation mode of the signal-recordingdevice 70 is a variable-frame-rate-recording mode, when a phasedifference is detected to have reached a recording start level on thebasis of the phase difference information AP supplied from therecording-processing unit, a control signal RM is supplied to arecording medium drive unit 82, thereby causing the recording mediumdrive unit 82 to drive the recording medium 90. Further, it controlsoperations of the storage-processing unit 73 using the control signalCUa, thereby causing the signals ME stored in the image memory 732 to beread in an order they have been written and supplied to the modulationunit 74. Further, it reads from the data memory 733 the signal MF ofadditional information relevant to the signal ME of a read frame imageand supplies it to the modulation unit 74. Furthermore, when the phasedifference is lowered to a recording stop level on the basis of thephase difference information AP, it stops reading of signals from theimage memory 732 and the data memory 733 as well as recording of signalsto the recording medium 90. Then, when a signal quantity of the signalsrecorded in the image memory 732 has reached a recording start level, itstarts recording signals to the recording medium 90 again. Similarly, ina variable frame rate recording mode, it records images intermittentlyto the recording medium 90 according to a quantity of the signalsrecorded in the image memory 732.

When the operation mode of the signal-recording device 70 is switchedfrom the variable frame rate recording mode to the stop mode on thebasis of the operation signal PSv, the recording control unit 80 stopswriting signals at the storage-processing unit 73 and reads signalsstored in the storage-processing unit 73 and records these signals tothe recording medium 90 and then ends the recording operation.

Further, the shooting device 10 and the signal-recording device 70 arenot limited to such one that can be controlled each in operation on thebasis of the operation signal from the input unit 61 or 81. For example,the shooting control unit 60 in the shooting device 10 and the recordingcontrol unit 80 in the signal-recording device 70 may communicate witheach other through the interface unit to control operations of the otherdevices on the basis of the operation signal supplied from the inputunit 61 in the shooting device 10 to the shooting control unit 60 orthat supplied from the input unit 81 in the signal-recording device 70to the recording control unit 80. In this case, the shooting device 10and the signal-recording device 70 need not each be operated but onlyone of them can be operated to perform recording, reproduction, etc. ofshot images.

The following will describe a signal-recording operation with referenceto a flowchart of FIG. 18. At step ST41, the process decides whether thevariable recording mode is selected. If the variable recording mode isnot selected by using the operation signal PSv from the input unit 81,the process goes to step ST42 to perform an ordinary recordingoperation, that is, the shooting device 10 makes the shooting frame rateconstant and avoids frame addition, to generate image signals eachhaving an output frame rate. The signal-recording device 70 sequentiallyrecords the image signals each having the output frame rate to therecording medium at a recording frame rate equivalent to the outputframe rate. Further, if the variable recording mode is selected, theprocess goes to step ST43.

At step ST43, the process decides whether a recording start operation isperformed based on the operation signal PSv from the input unit 81. Ifthe recording start operation is not performed, the process returns tostep ST43 and, otherwise, goes to step ST44.

At step ST44, the process starts the recording operation. That is, theprocess sequentially stores signals of frame images validated by thevalidity signal Tv to the recording-processing unit 73 and goes to stepST45. For example, the process selects an image signal of an imagehaving a variable frame rate “18P” validated by the validity signal Tvshown in FIG. 12G from the image signals DVj having an output frame rate“60P” shown in FIG. 12F and stores it in the storage-processing unit 73.

At step ST45, the process decides whether a recording end operation isperformed on the basis of the operation signal PSv. If the recording endoperation is not performed, the process goes to step ST46 and,otherwise, goes to step ST50.

At step ST46, the process decides whether a phase difference between awrite position and a read position of the signal ME on the image memory732 is increased to a recording start level “Lws (frame)”. If the phasedifference has not yet increased to the recording start level “Lws”, theprocess returns to step ST45. Otherwise, the process goes to step ST47.

At step ST47, the process starts an operation of recording an image oradditional information to the recording medium 90. For example, when therecording medium 90 is driven to enable the recording signal Sw to berecorded to the recording medium 90, the process reads the signals MEand MF recorded in the recording processing unit 73 to generate therecording signal Sw and supply this recording signal Sw to the headportion 75 to record the shot image or the additional information to therecording medium 90.

At step ST48, the process decides whether the phase difference betweenthe write position and the read position is lowered to a recording stoplevel “Lwe (frame)”. If the phase difference is yet to be lowered to therecording stop level “Lwe”, the process returns to step ST48. Otherwise,the process goes to step ST49.

At step ST49, the process stops recording the shot image and theadditional information to the recording medium. For example, the processsuspends reading the signals ME and MF stored in the storage-processingunit 73 and stops generation of the recording signal Sw. Further, when arecording medium not capable of random access such as a magnetic tape isused, the process stops driving the recording medium 90 and returns tostep ST45.

Then, the process ends the recording and goes from step ST45 to stepST50, where the process ends writing of the signals to the image memory732 and the data memory 733 and goes to step ST51.

At step ST51, the process records the signals left in therecording-processing unit 73 to the recording medium 90 to record allthe signals written in the memory of the storage-processing unit 73 tothe recording medium 90 and then goes to step ST52. At step ST52, theprocess ends the recording operation. That is, the process ends thesignal-reading operation at the storage processing unit 73 and endsdriving of the recording medium 90, to end the recording operation inthe variable recording mode.

FIGS. 19A-19B show write/read operations for signal performed to theimage memory 732; in FIG. 19A a solid line indicates a write positionfor a signal and a broken line indicates a read position for a signal.As shown in the figure, signals are written and read in a cyclic manner,that is, if the write or read position is at a final address, the signalis written or read respectively from a start address again. FIG. 19B, onthe other hand, shows a phase difference between the write position andthe read position.

When recording starts at time point t41, writing of the signal ME to theimage memory 732 starts, so that the phase difference increases as timeelapses. In this case, if the variable frame rate FRc is small in value,a small number of frames of an image are written to the image memory732, so that a gradient of the line that indicates the signal writeposition decreases.

If the write position increases in phase until the phase differencereaches the recording start level “Lws” at time point t42, the recordingcontrol unit 80 starts driving the recording medium 90. Then, at timepoint t43 when it is enabled the recording signal Sw to be recorded tothe recording medium 90, the process sequentially reads the storedsignals ME and MF from the image memory 732 to generate the recordingsignal Sw and record it to the recording medium 90 at a predeterminedrecording frame rate. In this case, the phase difference decreases if awrite operation is faster than a read operation to the image memory 732as in a case where, for example, the variable frame rate is “18P” andthe recording frame rate is “60P”.

Then, if the phase difference decreases to the recording stop level“Lwe” at time point t44, the process stops reading of the signals andstops recording of the signals to the recording medium 90. Further, ifthe phase difference increases due to stopping of the signal readoperation until it reaches the recording start level “Lws” at time pointt45, the process restarts driving the recording medium 90 to startreading a signal at time point t46 when it is enabled signals to berecorded to the recording medium 90. Similarly, the process records thesignals intermittently to the recording medium 90 in accordance with thephase difference between the write position and the read position forsignal.

By thus recording the signals to the recording medium 90 intermittently,it is possible to sequentially record signals of frame images for eachframe properly with some signals to be recorded being present always inthe recording medium during the signal recording even if the variableframe rate ERc is smaller than the recording frame rate.

Then, when the recording end operation is performed at time point t51,the process stops writing the signals to the image memory 732. Further,since signals as much as a phase difference are left in the image memory732 yet to be unrecorded to the recording medium 90, the process readsthese remaining signals and records them to the recording medium 90.Then, when the phase difference is reduced to zero at time point t52,the process ends reading the signals from the image memory 732, endsdriving of the recording medium 90, records the images up to a momentwhen the recording end operation is performed to the recording medium,and ends the recording operation.

In such a manner, the signal-recording device 70 uses an image signalhaving a predetermined output frame rate in which a shot image iscontained at a variable frame rate, to record this shot image having thevariable frame rate to the recording medium 90 at a recording framerate.

Further, although in this embodiment, to easily perform signal write andread operations to the image memory 732 for each frame image, the signalME has been written to the image memory 732 after its signal quantitybased on an encoded signal DQ is made equal for each frame, by managinga signal storage position for each frame image, the signal can bewritten and read for each frame image without equalizing the signalquantity of the signal ME for each frame.

For example, by managing the write starting position and write endingposition for signal for each frame image, to read signals from the imagememory 732, a signal of a desired frame image can be read on the basisof these starting position and ending position. In this case, since thesignal quantity of each frame image varies with contents of the image,by setting speeds of signal writing and reading operations to the imagememory 732 on the basis of the signal of a frame image having thelargest signal quantity, it is possible to properly write and read thesignal for each frame image even if the signal quantity fluctuates.

The following will describe display operations for displaying thereproduced image at the image display device 110 by reproducing the datafrom the recording medium 90 in which the shot image of variable framerate is recorded at the recording frame rate.

FIG. 20 explains a reproduction operation in the case of reproducing atframe rate “24P” the recording medium 90 in which an image indicated tobe valid by the validity signal Tv is recorded at, for example, framerate “60P”.

In a period from time point t61 to time point t62 during the image isreproduced, which has been shot at a set value of variable frame rate“18P”, in the image signal MTout obtained by reproducing the recordingmedium 90, an image shot at variable frame rate “18P” is displayed at amultiplied-by-“24/18 (≈1.33)” speed with respect to the shot speed.Therefore, the image is displayed at the image display device 110 at ahigh playback speed of about 1.33 times the shot speed. Further, in aperiod from time point t62 to time point t63 during the image isreproduced, which has been shot at a set value of variable frame rate“24P”, the reproduction frame rate and the variable frame rate are equalto each other, so that the image is reproduced at a multiplied-by-1speed with respect to the shot speed. In a period from time point t63 totime point t64 during the image is reproduced, which has been shot at aset value of variable frame rate “48P”, the image shot at variable framerate “48P” is displayed at a multiplied-by-“24/48(=½)” speed withrespect to the shot speed. Therefore, the displayed image is reproducedslowly at half the shot speed. Further, additional information isrecorded in the recording medium 90 together with the images, so that itis possible to easily know on the basis of the additional informationMDr on which shooting conditions each of frame images of thevariable-speed playback images has been shot, etc.

If, in such a manner, a signal validated by the validity signal Tv isselected from among image signals obtained through shooting at variousvariable frame rates and recorded to the recording medium 90 at arecording frame rate, when contents of this recording medium 90 arereproduced at a desired frame rate, a signal capable of obtaining avariable-speed playback image that matches the variable frame rate isrecorded to the recording medium 90. Therefore, only by reproducing at adesired frame rate a signal recorded in the recording medium 90, specialvideo effects can be confirmed easily and speedily without recording theimage signal in a server etc. and processing images.

Further, an image validated by the validity signal Tv is selected andrecorded, so that only a variable-speed playback image is recorded inthe recording medium 90. Therefore, it is unnecessary to record all ofimage signals having a shooting frame rate conventionally, so that, forexample, a server etc. not having a large recording capacity can beused.

PROBABILITY OF UTILIZED INDUSTRIALIZATION

As described above, according to a shot-image-recording system and asignal-recording device and method related to the present invention,signal recording is executed using an image signal having apredetermined output frame rate in which images each having a variableframe rate are contained and a validity signal indicating frames of theimages having the variable frame rate with respect to this image signal;on the basis of this validity signal, image signals of the images havingthe variable frame rate are selected from among the image signals andstored in storage means, so that in accordance with a signal quantity ofthe image signals stored in the storage means, the signals stored in thestorage means are intermittently recorded to a recording medium at apredetermined recording frame rate. Therefore, to obtain special videoeffects, fewer image signals of shot images are required to be recordedand these special video effects can be conformed speedily and properly,so that the present invention is useful in production of a movie and aTV program and well applicable especially in obtaining special videoeffects.

1. A shot-image-recording system comprising a shooting device forshooting an object and a signal-recording device for recording in arecording medium an image obtained by shooting the object with theshooting device, wherein said shooting device comprises: shooting meansfor generating an image signal having a shooting frame rate from a shotimage; frame-addition-processing means for adding a frame on the basisof the image signal generated by the shooting means to obtain an imagesignal having an output frame rate in which the shot image is containedat a variable frame rate and outputting said image signal having theoutput frame rate and a validity signal indicating frame of the imagehaving the variable frame rate in said image signal having the outputframe rate; and shooting control means for controlling operations of theshooting means and the frame-addition-processing means on the basis of aframe-rate-setting signal, to control varying of the shooting frame rateand/or switching of the number of add frames in the frame addition sothat the variable frame rate may be set to a frame rate based on theframe-rate-setting signal, and wherein the signal-recording devicecomprises: storage means for storing the image signal temporarily;storage control means for selecting an image signal of the image havingthe variable frame rate from among the image signal having the outputframe rate on the basis of said validity signal and storing it in thestorage means; recording means for recording a signal in the recordingmedium; and recording control means for recording the signal stored inthe storage means in the recording medium intermittently at apredetermined recording frame rate in accordance with a signal quantityof the image signal stored in the storage means.
 2. Theshot-image-recording system according to claim 1, wherein the recordingcontrol means uses a phase difference between a write position and aread position for the signal as the signal quantity of the image signalstored in the storage means.
 3. The shot-image-recording systemaccording to claim 1, wherein the signal-recording device furthercomprises image compression means; wherein the image compression meanscompresses the image signal of the image having the variable frame rate;and wherein the storage control means stores the compressed image signalin the storage means.
 4. The shot-image-recording system according toclaim 1, wherein the shooting control means generates additionalinformation relevant to the image having the variable frame rate; andwherein the storage control means stores the image signal of the imagehaving the variable frame rate and the additional information in thestorage means.
 5. The shot-image-recording system according to claim 1,wherein the image signal having the output frame rate is a signal of acommon data rate (CDR) system.
 6. A signal-recording device forrecording a signal using an image signal having an output frame rate inwhich an image having a variable frame rate is contained and a validitysignal indicating a frame of the image having the variable frame ratewith respect to the image signal, comprising: storage means for storingthe image signal temporarily; storage control means for selecting theimage signal of the image having the variable frame rate from among theimage signal on the basis of the validity signal and storing it in thestorage means; recording means for recording the signal in the recordingmedium; and recording control means for recording the signal stored inthe storage means in the recording medium intermittently at apredetermined recording frame rate in accordance with a signal quantityof the image signal stored in the storage means.
 7. The signal-recordingdevice according to claim 6, wherein the recording control means uses aphase difference between a write position and a read position for thesignal as the signal quantity of the image signals stored in the storagemeans.
 8. The signal-recording device according to claim 6, furthercomprising image compression means, wherein the image compression meanscompresses the image signal of the image having the variable frame rate;and wherein the storage control means stores the compressed image signalin the storage means.
 9. The signal-recording device according to claim6, wherein the image signal having the predetermined output frame rateis a signal of a common data rate (CDR) system.
 10. A signal-recordingmethod for recording a signal using an image signal having an outputframe rate in which an image having a variable frame rate is containedand a validity signal indicating a frame of the image having thevariable frame rate with respect to this image signal, said methodcomprising the steps of: selecting the image signal of the image havingthe variable frame rate from among the image signal on the basis of thevalidity signal and storing it in the storage means; and recording thesignal stored in the storage means in the recording mediumintermittently at a predetermined recording frame rate in accordancewith a signal quantity of the image signal stored in the storage means.11. The signal-recording method according to claim 10, wherein a phasedifference between a write position and a read position for the signalis used as the signal quantity of the stored image signal.
 12. Thesignal-recording method according to claim 10, further comprising thestep of compressing the image signal of the image having the variableframe rate, and storing the compressed image signal in the storagemeans.
 13. The signal-recording method according to claim 10, whereinthe image signal having the output frame rate is a signal of a commondata rate (CDR) system.